linux-kernel - Re: [PATCH] tpm: fixes uninitialized allocated banks for IBM vtpm driver

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Date:   Fri, 05 Jul 2019 20:50:27 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Nayna <nayna@...ux.vnet.ibm.com>,
        Stefan Berger <stefanb@...ux.ibm.com>,
        Nayna Jain <nayna@...ux.ibm.com>,
        linux-integrity@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Cc:     Sachin Sant <sachinp@...ux.vnet.ibm.com>,
        Michal Suchanek <msuchanek@...e.de>,
        linux-kernel@...r.kernel.org, Mimi Zohar <zohar@...ux.ibm.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Peter Huewe <peterhuewe@....de>,
        George Wilson <gcwilson@...ux.ibm.com>
Subject: Re: [PATCH] tpm: fixes uninitialized allocated banks for IBM vtpm
 driver

On Fri, 2019-07-05 at 11:32 -0400, Nayna wrote:
> I am not sure of the purpose of tpm_stop_chip(), so I have left it as it 
> is. Jarkko, what do you think about the change ?

Stefan right. Your does not work, or will randomly work or not work
depending on the chip.

You need to turn the TPM on with tpm_chip_start() and turn it off with
tpm_chip_stop() once you are done. This is done in tpm_chip_register()
before calling tpm_auto_startup().

TPM power management was once in tpm_transmit() but not anymore after my
patch set that removed nested tpm_transmit() calls.

While you're on it please take into account my earlier feedback.

Also, short summary could be "tpm: tpm_ibm_vtpm: Fix unallocated banks"

Some oddballs in your patch that I have to ask.

if (chip->flags & TPM_CHIP_FLAG_TPM2) {
	rc = tpm2_get_pcr_allocation(chip);
	if (rc)
		goto out;
}

chip->allocated_banks = kcalloc(1, sizeof(*chip->allocated_banks),
		GFP_KERNEL);
if (!chip->allocated_banks) {
	rc = -ENOMEM;
	goto out;
}

Why you don't return on site and instead jump somewhere? Also the
2nd line for kcalloc() is misaligned.

out:
	if (rc < 0)
		rc = -ENODEV;

This will cause a new regression i.e. you let TPM error codes
through.

To summarize this patch fixes one regression and introduces two
completely new ones...

/Jarkko`